(CNN) -- A professor who compared some victims of the al Qaeda attack on the World Trade Center to Nazis was fired Tuesday by the University of Colorado's Board of Regents.

Professor Ward Churchill wrote that some 9/11 victims were "little Eichmanns."

Ward Churchill raised hackles with a 2002 essay that argued the September 11, 2001, attacks were a justified reaction to U.S. policies in the Middle East, and said the hijackers who killed nearly 3,000 people in New York, Washington and Pennsylvania had "the courage of their convictions."

But the regents said Churchill's firing was unrelated to the essay, which went largely unnoticed for three years. Instead, it cited "deliberate and repeated research misconduct." A university investigation had found cases of plagiarism and falsification in previous papers by Churchill -- allegations that surfaced after his essay became widely known.

"The Board of Regents affirms that its decisions in this matter have been made solely on the basis of the allegations of research misconduct against Professor Churchill and have not been influenced or motivated by extrinsic considerations, Professor Churchill's political and social views or a desire to punish Professor Churchill for expression of his political or social views," the university announced.

CU interim Chancellor Phil DiStefano recommended Churchill's dismissal in June 2006 after a university committee completed its investigation.

Churchill's essay drew little notice until a 1,800-student college in upstate New York invited him to take part in a 2005 forum on prisons and Native American rights. The invitation was rescinded after criticism from then-New York Gov. George Pataki, then-Colorado Gov. Bill Owens and hundreds of relatives of those killed in the attacks created a media firestorm.

The piece had called some of those who died in the World Trade Center "little Eichmanns" -- a reference to Adolf Eichmann, the Gestapo officer who was one of the chief architects of the Holocaust -- arguing they were "a technocratic corps at the very heart of America's global financial empire."

Churchill, who had tenure, stepped down from his post as head of CU's ethnic studies department amid the flap but remained on staff. He had no immediate reaction to Tuesday's decision.E-mail to a friend